1. Technical Field
This disclosure relates generally to image forming apparatuses, and more particularly to an image forming apparatus having a manual paper feed part.
2. Description of the Related Art
Known as image forming apparatuses such as printers, facsimile machines, copiers, and printer/facsimile machine/copier multifunction apparatuses are, for example, an inkjet recording apparatus performing image formation by attaching liquid droplets of recording liquid to a recording target medium (a medium on which recording is to be performed) while conveying the medium, using a recording head (image forming part) formed of a liquid ejection head ejecting the liquid droplets of the recording liquid; and an electrophotographic image forming apparatus performing image formation by electrophotography.
In the following description, synonyms of “image formation” may include “recording” and “printing.” Further, “liquid droplet” may also be referred to as “ink droplet.” Further, “recording target medium” may also be referred to as, but not limited in material to, “paper,” and synonyms of “recording target medium” may include “recording medium” and “transfer material.”
As shown in, for example, Japanese Laid-Open Patent Application Nos. 3-138256 (Document 1), 9-235029 (Document 2), and 10-17179 (Document 3), the image forming apparatus has multiple paper feed parts in order to feed paper for image formation to the main body of the apparatus, such as a paper feed tray on which multiple sheets of paper are placeable, a paper feed cassette capable of containing a large amount of paper, and one or more types of manual paper feed trays (parts) for allowing a user to directly feed paper manually, for example, one capable of receiving multiple sheets of paper and another capable of receiving a single sheet of paper.
Further, as shown in Japanese Patent No. 2698699 (Document 4) and Japanese Laid-Open Patent Application No. 2000-211768 (Document 5), some image forming apparatuses allow paper to be fed from a paper output tray, and output the paper again onto the paper output tray after forming an image thereon, thereby omitting a manual paper feed part.
Further, Japanese Utility Model Registration No. 3060361 (Document 6) discloses an image forming apparatus that feeds paper fed from a manual paper feed opening to a printing part, and after printing, conveys the paper again to the manual paper feed opening and outputs the paper.
Further, Japanese Examined Utility Model Application Publication No. 7-3403 (Document 7) discloses an image forming apparatus including a retractable manual paper feed table and a blocking member that moves up and down in conjunction with the opening and closing of the manual paper feed table so as to move down when the manual paper feed table is opened to a manual paper feed position, thereby putting a manual feed detection part in or out of operation. When paper is fed to the manual paper feed table at the manual paper feed position, a blocking member for paper detection leaves a paper detection part. As a result, performability of paper feeding is detected and displayed.
Further, Japanese Laid-Open Patent Application No. 6-64792 (Document 8) discloses an image forming apparatus that performs registration by forming a loop in paper and feeds the paper to an image forming part through a registration roller device.
Further, Japanese Patent No. 2702533 (Document 9) discloses an image forming apparatus that employs switch-back printing. According to this apparatus, paper having printing on one side thereof is turned upside down and fed so that printing is performed on the other side of the paper. After having both sides subjected to printing, the paper is output onto a paper output tray.
Further, Japanese Laid-Open Patent Application No. 8-110660 (Document 10) discloses an image forming apparatus reduced in size by disposing a paper feed cassette below a reading part.
However, for example, in the image forming apparatuses disclosed in Documents 1 and 2 described above, when either manual paper feed tray is ready to feed paper manually, manual paper feeding is performable. Accordingly, if manual paper feeding is performed while paper on which image formation is being performed is remaining in the apparatus, multiple sheets of paper may be conveyed one over another, so that a paper jam may be caused. Likewise, in the image forming apparatus shown in Document 4, in which the paper output tray is also used as a manual feed tray, a paper jam may also occur if paper on which an image has been formed is output from inside the apparatus when paper is manually fed from the paper output tray.
Further, image forming apparatuses such as inkjet recording apparatuses employ paper output methods such as straight paper output and face-down paper output. According to straight paper output, paper is fed straight, and after an image is formed thereon, the paper is conveyed straight to be output with its print side (on which the image is formed) facing upward. According to face-down output, paper is reversed (turned upside down) after an image is formed thereon, and is output with its print side facing downward. In the image forming apparatus performing straight paper output, the entire apparatus including output paper takes up a large space. On the other hand, in the image forming apparatus performing reverse (face-down) paper output, in the case of performing printing on paper on which ink dries less easily, such as an OHP sheet, the print side of the paper may rub on a guide member at the time of reversal of the paper, thus resulting in a degraded image. Further, in the case of using thick paper, possible failure in paper reversal may cause a paper jam.
Accordingly, it is preferable to provide, apart from a regular paper feed tray and manual paper feed part, a single-sheet manual paper feed part for straight manual paper feeding, and it is preferable to provide a straight paper output tray for straight paper conveyance and output. In this case, the single-sheet manual paper feed part and the straight paper output tray may be provided so as to be retractable relative to the apparatus main body in order to prevent an increase in the space taken up by the apparatus.
In the case of thus providing a single-sheet manual paper feed part for manually feeding a single sheet of paper, if the same configuration as the image forming apparatus shown in Document 6, where the manual paper feed opening is also used as a paper output opening, or the image forming apparatuses shown in Documents 4 and 5, where the paper output tray is also used as a manual feed tray, is employed, a paper jam may occur if paper is fed from the manual paper feed opening or the paper output tray with paper remaining in the apparatus.
Further, in the case of providing a straight paper output tray, if the straight paper output tray is left unable to output paper, straight paper output cannot be performed when a single sheet of paper is manually fed, so that a paper jam may also occur. Further, if it is so configured as to prevent paper from being fed in such a case, a user may not know the reason for no paper feeding, and may mistake it for failure. Thus, the user interface may be degraded.